“Charlotte believes that Marty understands the struggles of working people because he has lived through it,” said one of the people, who spoke to Golar Richie after the call. “She knows that he will stand up for the people who have been marginalized and disenfranchised because those people are his neighbors.”

Golar Richie received almost 14 percent of the vote in the preliminary election, and her backing had been heavily courted by Walsh and his opponent, City Councilor John R. Connolly. She made her decision Friday evening, according to people with knowledge of her decision, who spoke on the condition of anonymity.

The endorsement will be announced Saturday, one of the people said. Golar Richie did not return a phone message. Walsh and Connolly also did not comment.